Racket implementation of Python.

Overview
--------

We are testing our implementation against the unit tests of Python
3.2.3:

http://www.python.org/download/releases/3.2.3/

The source link is at:

http://www.python.org/ftp/python/3.2.3/Python-3.2.3.tgz

The tests in python-reference/ were drawn from the unit tests in the
Lib/tests directory of that source bundle.

This Repo
---------

base/

  This contains the base implementation we'll be working from (thanks
  Sumner, Andrew, and Nathan!).  It looks a lot like cs173-python; you
  should have a look at that directory's README to get started
  understanding that implementation.  This is the implementation folks
  should start building from.

scope/

  This contains the implementation of Kelvin and Victor (thanks guys!),
  that has the model of scope we'll be attaching to the implementation
  in base/.